Copy only the spans we are interested in.

The PARAGRAPH type of span is dangerous, as concatenating
CharSequences that contain it may crash. We also don't use
other spans than SuggestionSpans, so we don't copy them.

Bug: 10622489
Change-Id: If4e44eca3cdc5bb02cf2e0c8c44ecd4bf27fae57

2 files changed, 94 insertions, 2 deletions

diff --git a/java/src/com/android/inputmethod/latin/RichInputConnection.java b/java/src/com/android/inputmethod/latin/RichInputConnection.java
index fa7f23efb..925381b50 100644
--- a/java/src/com/android/inputmethod/latin/RichInputConnection.java
+++ b/java/src/com/android/inputmethod/latin/RichInputConnection.java
@@ -607,8 +607,11 @@ public final class RichInputConnection {
             }
         }
 
-        return new TextRange(TextUtils.concat(before, after), startIndexInBefore,
-                before.length() + endIndexInAfter, before.length());
+        // We don't use TextUtils#concat because it copies all spans without respect to their
+        // nature. If the text includes a PARAGRAPH span and it has been split, then
+        // TextUtils#concat will crash when it tries to concat both sides of it.
+        return new TextRange(StringUtils.concatWithNonParagraphSuggestionSpansOnly(before, after),
+                startIndexInBefore, before.length() + endIndexInAfter, before.length());
     }
 
     public boolean isCursorTouchingWord(final SettingsValues settingsValues) {
diff --git a/java/src/com/android/inputmethod/latin/utils/StringUtils.java b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
index 121aecf0f..327780ad0 100644
--- a/java/src/com/android/inputmethod/latin/utils/StringUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
@@ -20,7 +20,12 @@ import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.latin.Constants;
 import com.android.inputmethod.latin.settings.SettingsValues;
 
+import android.text.Spannable;
+import android.text.SpannableString;
+import android.text.Spanned;
+import android.text.SpannedString;
 import android.text.TextUtils;
+import android.text.style.SuggestionSpan;
 import android.util.JsonReader;
 import android.util.JsonWriter;
 import android.util.Log;
@@ -462,4 +467,88 @@ public final class StringUtils {
         }
         return "";
     }
+
+    /**
+     * Copies the spans from the region <code>start...end</code> in
+     * <code>source</code> to the region
+     * <code>destoff...destoff+end-start</code> in <code>dest</code>.
+     * Spans in <code>source</code> that begin before <code>start</code>
+     * or end after <code>end</code> but overlap this range are trimmed
+     * as if they began at <code>start</code> or ended at <code>end</code>.
+     * Only SuggestionSpans that don't have the SPAN_PARAGRAPH span are copied.
+     *
+     * This code is almost entirely taken from {@link TextUtils#copySpansFrom}, except for the
+     * kind of span that is copied.
+     *
+     * @throws IndexOutOfBoundsException if any of the copied spans
+     * are out of range in <code>dest</code>.
+     */
+    public static void copyNonParagraphSuggestionSpansFrom(Spanned source, int start, int end,
+                                     Spannable dest, int destoff) {
+        Object[] spans = source.getSpans(start, end, SuggestionSpan.class);
+
+        for (int i = 0; i < spans.length; i++) {
+            int fl = source.getSpanFlags(spans[i]);
+            if (0 != (fl & Spannable.SPAN_PARAGRAPH)) continue;
+
+            int st = source.getSpanStart(spans[i]);
+            int en = source.getSpanEnd(spans[i]);
+
+            if (st < start)
+                st = start;
+            if (en > end)
+                en = end;
+
+            dest.setSpan(spans[i], st - start + destoff, en - start + destoff,
+                         fl);
+        }
+    }
+
+    /**
+     * Returns a CharSequence concatenating the specified CharSequences, retaining their
+     * SuggestionSpans that don't have the PARAGRAPH flag, but not other spans.
+     *
+     * This code is almost entirely taken from {@link TextUtils#concat(CharSequence...)}, except
+     * it calls copyNonParagraphSuggestionSpansFrom instead of {@link TextUtils#copySpansFrom}.
+     */
+    public static CharSequence concatWithNonParagraphSuggestionSpansOnly(CharSequence... text) {
+        if (text.length == 0) {
+            return "";
+        }
+
+        if (text.length == 1) {
+            return text[0];
+        }
+
+        boolean spanned = false;
+        for (int i = 0; i < text.length; i++) {
+            if (text[i] instanceof Spanned) {
+                spanned = true;
+                break;
+            }
+        }
+
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < text.length; i++) {
+            sb.append(text[i]);
+        }
+
+        if (!spanned) {
+            return sb.toString();
+        }
+
+        SpannableString ss = new SpannableString(sb);
+        int off = 0;
+        for (int i = 0; i < text.length; i++) {
+            int len = text[i].length();
+
+            if (text[i] instanceof Spanned) {
+                copyNonParagraphSuggestionSpansFrom((Spanned) text[i], 0, len, ss, off);
+            }
+
+            off += len;
+        }
+
+        return new SpannedString(ss);
+    }
 }